In the field of medicine, before effective treatment can be prescribed, physicians normally run or have run series of tests to determine the nature of the illness, infection, or disease. Such tests, in many cases, are run on diseased tissue. This, in fact, requires the physician to obtain a specimen of the infected or diseased tissue in the most efficient manner with the least discomfort to the patient. Various biopsy methods are used to obtain these needed tissue samples.
Biopsies are performed using an open or a closed technique. Open biopsy removes the entire mass (excision biopsy) or a part of the mass (incision biopsy). Closed biopsy is usually done with a needle-like instrument and may be either an aspiration or a core biopsy. In needle aspiration biopsy, individual cells or clusters of cells are obtained for cytologic examination and may be prepared such as in a Papanicolaou smear. In core biopsy, a core or filament of tissue is obtained for histologic examination which may be done via a frozen section or paraffin section. The type of biopsy that is used depends on the circumstances; however, core biopsy is extremely useful in a number of conditions and is the most widely used type of biopsy.
A well known instrument used for core biopsies is manufactured by Travenol Laboratories of Deerfield, Illinois and is sold under the trademark "TRUCUT." This instrument has a two piece assembly: an outer cutting cannula mounted to a hub and an inner stylet (with a specimen notch ground into it) mounted to a second hub. The two hubs are slideably interlocked.
The instrument is assembled and placed into the area of the body of interest with the outer cutting cannula just to the rear of a lancet point or beveled distal end of the stylet. The instrument is inserted up to or in front of the area to be biopsied. The stylet is then manually advanced distally in the cannula with the cannula held stationary. When the stylet is advanced into the area to be biopsied, the specimen notch is exposed and the tissue surrounding the stylet contacts the specimen notch. The outer cannula is then manually advanced distally over the stylet. This will shear off tissue which will be trapped in the specimen notch. The instrument is withdrawn with the cannula and stylet in this last position. Once the instrument is removed, the tissue specimen can be removed by advancing the stylet from within the cannula and the specimen can be tested.
The technique just described is a manual technique that requires a great deal of manual dexterity and motor coordination. Moreover, it requires two hands to properly operate the instrument to obtain tissue specimens. The need to use two hands to perform this technique is a disadvantage. Further, this instrument is not reusable.
The procedure just described is somewhat complicated and there is a danger of inadvertently moving the wrong member at the wrong time. This is manifest in the two members--the stylet and cutting cannula--being at times movable together and at other times movable relative to each other to obtain tissue specimens. The person performing the biopsy inadvertently may fail to use the proper sequence of movements to effect the procedure. This can result in damage to the patient or a failure to obtain the specimen, which will require a second insertion.
The present invention overcomes the problems just described and provides a system which will permit a physician or other professional to obtain a core tissue specimen requiring the use of only one hand (allowing the other to be free for other work) and permit controlled insertion of the needle assembly to reduce the risk to the patient.